ERFC

This function evaluates the complementary error function.

Function Return Value

ERFC — Function value. (Output)

Required Arguments

X — Argument for which the function value is desired. (Input)

FORTRAN 90 Interface

Generic: ERFC (X)

Specific: The specific interface names are S_ERFC and D_ERFC.

FORTRAN 77 Interface

Single: ERFC (X)

Double: The double precision function name is DERFC.

Description

The complementary error function, erfc(x), is defined to be

 

The argument x must not be so large that the result underflows. Approximately, x should be less than

 

where s = AMACH(1) (see the Reference Material section of this manual) is the smallest representable positive floating‑point number.

 

Figure 1,  Plot of erfc (x)

Comments

Informational Error

 

Type	Code	Description
2	1	The function underflows because X is too large.

Example

In this example, erfc(1.0) is computed and printed.

 

USE ERFC_INT

USE UMACH_INT

 

IMPLICIT NONE

! Declare variables

INTEGER NOUT

REAL VALUE, X

! Compute

X = 1.0

VALUE = ERFC(X)

! Print the results

CALL UMACH (2, NOUT)

WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' ERFC(', F6.3, ') = ', F6.3)

END

Output

 

ERFC( 1.000) = 0.157